Add a new item to existing list and save it and Dot indexing is not supported for variables of this type

Hi,

I am developping an app for EV's. i am looking for a way to allow the future users to add new vehicles to the drop down menu. To do this, i need a code to modify the existing item list, and add new EVs referances. I found this code, i modified a bit and it somehow works

However ! when i close the app the name desepears, and i have to start again. What i am i missing ?, and how to make the code saves the new car, in the existing database without deleting it after restart

thank you

            new_car = "WhatEver";
            app.VehicleModelDropDown.Items = [app.VehicleModelDropDown.Items new_car];
            

Answer 1

[Mohammad Sami]

You need to load and save Items from a .mat file if you wish your changes to be persisted across runs. Otherwise the items will always initialise to the values you have coded in your app.

[Khalala Mamouri]

Can you Give me an exemple please ?

[Mohammad Sami]

Add a startupFcn to your app. This can be done by going into the code view and clicking App Input Arguments.

It will open a dialog, type "varargin" and click ok. It will create the startupFcn.

        % Code that executes after component creation
        function startupFcn(app, varargin)
            list = load('VehicleList.mat');
            app.VehicleModelDropDown.Items = list.VehicleList;
        end
        
        function UpdateVehicleList(app,new_car)
            VehicleList = [app.VehicleModelDropDown.Items new_car];
            save('VehicleList.mat','VehicleList','-append');
            app.VehicleModelDropDown.Items = VehicleList;
        end

[Khalala Mamouri]

Hi mohammad thanks for the fast replay and code.

Unfortunately i run in some problems using the load function so a changed a bit the code, but still the same idea as yours. So i am using "fopen" instead of "load" and a .m file unstead of .mat. As i said i think the principal is the same for both, how ever, when i start simulation i get this error :

" Dot indexing is not supported for variables of this type "

The code i am using is given bellow.

        function startupFcn(app, varargin)
            evalin('base', 'clear all')   
            evalin('base', 'clc') 
            
        
            list = fopen('VehicleList.m','r'); % Read data from the file
            A = textscan(list, '%c');          % Importing data
            fclose(list);                      % close file 
            AB = char(A);                      % Cell to char conversion
            assignin('base','A', A);           % send to workspace
            assignin('base','AB', AB);         % send to workspace
            app.VehicleModelDropDown.Items = AB.VehicleList; % << I get the error here
        
        
        function UpdateVehicleList(app,new_car)
            VehicleList = [app.VehicleModelDropDown.Items new_car];
            save('VehicleList.m','VehicleList','-append');
            app.VehicleModelDropDown.Items = VehicleList;
        end
        end
        
        Thanks for your time ;)